commit 96e5d1d3adf56f1c7eeb07258f6a1a0a7ae9c489 upstream. In gfs2_trans_add_bh(), gfs2 was testing if a there was a bd attached to the buffer without having the gfs2_log_lock held. It was then assuming it would stay attached for the rest of the function. However, without either the log lock being held of the buffer locked, __gfs2_ail_flush() could detach bd at any time. This patch moves the locking before the test. If there isn't a bd already attached, gfs2 can safely allocate one and attach it before locking. There is no way that the newly allocated bd could be on the ail list, and thus no way for __gfs2_ail_flush() to detach it. Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com> [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Pull gfs2 changes from Steven Whitehouse. * git://git.kernel.org/pub/scm/linux/kernel/git/steve/gfs2-3.0-nmw: GFS2: Change truncate page allocation to be GFP_NOFS GFS2: call gfs2_write_alloc_required for each chunk GFS2: Clean up log flush header writing GFS2: Remove a __GFP_NOFAIL allocation GFS2: Flush pending glock work when evicting an inode GFS2: make sure rgrps are up to date in func gfs2_blk2rgrpd GFS2: Eliminate sd_rindex_mutex GFS2: Unlock rindex mutex on glock error GFS2: Make bd_cmp() static GFS2: Sort the ordered write list GFS2: FITRIM ioctl support GFS2: Move two functions from log.c to lops.c GFS2: glock statistics gathering
Signed-off-by: Cong Wang <amwang@redhat.com>
In order to ensure that we've got enough buffer heads for flushing the journal, the orignal code used __GFP_NOFAIL when performing this allocation. Here we dispense with that in favour of using a mempool. This should improve efficiency in low memory conditions since flushing the journal is a good way to get memory back, we don't want to be spinning, waiting on memory allocations. The buffers which are allocated via this mempool are fairly short lived, so that we'll recycle them pretty quickly. Although there are other memory allocations which occur during the journal flush process, this is the one which can potentially require the most memory, so the most important one to fix. The amount of memory reserved is a fixed amount, and we should not need to scale it when there are a greater number of filesystems in use. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
The FITRIM ioctl provides an alternative way to send discard requests to the underlying device. Using the discard mount option results in every freed block generating a discard request to the block device. This can be slow, since many block devices can only process discard requests of larger sizes, and also such operations can be time consuming. Rather than using the discard mount option, FITRIM allows a sweep of the filesystem on an occasional basis, and also to optionally avoid sending down discard requests for smaller regions. In GFS2 FITRIM will work at resource group granularity. There is a flag for each resource group which keeps track of which resource groups have been trimmed. This flag is reset whenever a deallocation occurs in the resource group, and set whenever a successful FITRIM of that resource group has taken place. This helps to reduce repeated discard requests for the same block ranges, again improving performance. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
gfs2_log_get_buf() and gfs2_log_fake_buf() are both used only in lops.c, so move them next to their callers and they can then become static. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Some items picked up through automated code analysis. A few bits of unreachable code and two unchecked return values. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Here is an update of Bob's original rbtree patch which, in addition, also resolves the rather strange ref counting that was being done relating to the bitmap blocks. Originally we had a dual system for journaling resource groups. The metadata blocks were journaled and also the rgrp itself was added to a list. The reason for adding the rgrp to the list in the journal was so that the "repolish clones" code could be run to update the free space, and potentially send any discard requests when the log was flushed. This was done by comparing the "cloned" bitmap with what had been written back on disk during the transaction commit. Due to this, there was a requirement to hang on to the rgrps' bitmap buffers until the journal had been flushed. For that reason, there was a rather complicated set up in the ->go_lock ->go_unlock functions for rgrps involving both a mutex and a spinlock (the ->sd_rindex_spin) to maintain a reference count on the buffers. However, the journal maintains a reference count on the buffers anyway, since they are being journaled as metadata buffers. So by moving the code which deals with the post-journal accounting for bitmap blocks to the metadata journaling code, we can entirely dispense with the rather strange buffer ref counting scheme and also the requirement to journal the rgrps. The net result of all this is that the ->sd_rindex_spin is left to do exactly one job, and that is to look after the rbtree or rgrps. This patch is designed to be a stepping stone towards using RCU for the rbtree of resource groups, however the reduction in the number of uses of the ->sd_rindex_spin is likely to have benefits for multi-threaded workloads, anyway. The patch retains ->go_lock and ->go_unlock for rgrps, however these maybe also be removed in future in favour of calling the functions directly where required in the code. That will allow locking of resource groups without needing to actually read them in - something that could be useful in speeding up statfs. In the mean time though it is valid to dereference ->bi_bh only when the rgrp is locked. This is basically the same rule as before, modulo the references not being valid until the following journal flush. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com> Signed-off-by: Bob Peterson <rpeterso@redhat.com> Cc: Benjamin Marzinski <bmarzins@redhat.com>
The GLF_LRU flag introduced in the previous patch can be used to check if a glock is on the lru list when a new holder is queued and if so remove it, without having first to get the lru_lock. The main purpose of this patch however is to optimise the glocks left over when an inode at end of life is being evicted. Previously such glocks were left with the GLF_LFLUSH flag set, so that when reclaimed, each one required a log flush. This patch resets the GLF_LFLUSH flag when there is nothing left to flush thus preventing later log flushes as glocks are reused or demoted. In order to do this, we need to keep track of the number of revokes which are outstanding, and also to clear the GLF_LFLUSH bit after a log commit when only revokes have been processed. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
Rather than allowing the glocks to be scheduled for possible reclaim as soon as they have exited the journal, this patch delays their entry to the list until the glocks in question are no longer in use. This means that we will rely on the vm for writeback of all dirty data and metadata from now on. When glocks are added to the lru list they should be freeable much faster since all the I/O required to free them should have already been completed. This should lead to much better I/O patterns under low memory conditions. Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>